Anatomy of the Dicotyledons.
About: This article is published in American Midland Naturalist.The article was published on 1950-11-01. It has received 2511 citations till now.
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TL;DR: Secondary xylem of opuntias with cylindrical to globular stems is described for 30 species from the major phylads and the full range of growth habits, suggesting that fluctuations in levels of growth substances determine these ontogenetic patterns.
Abstract: Secondary xylem of opuntias with cylindrical to globular stems is described for 30 species from the major phylads and the full range of growth habits. The majority of these cacti produce highly specialized stem and root woods that have vessel elements with alternate pits and libriform fibers. Seven mostly small caespitose species belonging to phyletic lines in North and South America have stem secondary xylem composed of vessel elements with helical to reticulate secondary thickenings and vascular tracheids with only annular secondary thickenings but no fibers. In three South American species with nonfibrous stem woods, lateral-root woods are fibrous, and Opuntia tunicata of North America exhibits fibrous xylem in outer regions of old stems. Based on small sample sizes, mean lengths and diameters of axial elements show no consistent correlations with plant size, habit, or geographical origin. Within an individual, vessel-element length and diameter are generally greatest in small lateral roots. Intrusive ...
39 citations
TL;DR: The course of development of the glandular and non-glandular hairs of Avicennia marina was found to be the same up to the three-celled stage and it is concluded that the two types are phylogenetically related.
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TL;DR: Results of the cladistic analysis of Onagraceae support a sister group relationship of Ludwigia to the rest of the genera, and it is concluded that the tribe Onagreae rnay be paraphyletic.
Abstract: A cladistic analysis of Onagraceae was perforrned using 17 characters frorn rnor phology, anatorny, palynology, ernbryology, and cytology, with its 16 genera as the terminal taxa, and with several possible outgroups within Myrtales. In the rnain analysis (all Myrtales as outgroup ), seven equally parsirnonious cladograrns were produced, each with 29 steps and a consistency index of 0.82. A successive weighting procedure was applied, resulting in six cladograrns with a consistency index of 0.93. All cladograrns share the following nine rnonophyletic groups: 1) all taxa except Ludwigia; 2) Circaea (Fuchsia-Lopezia); 3) Fuchsia-Lopezia; 4) Gayophytum (Epilobium-Boisduvalia) (Gongylocarpus-Xylonagra-Camissonia(Clarkia(Hauya-Calylophus-Gaura)) (Oenothera-Stenosiphon)); 5) Epilobium-Boisduvalia; 6) Gongylocarpus-X y Ionagra-Camissonia( Clarkia(H auya-Calylophus Gaura ))(Oenothera-Stenosiphon ); 7) Clarkia(Hauya-Calylophus-Gaura); 8) Hauya-Calylophus-Gaura; and 9) Oenothera-Stenosiphon. One additional rnonophyletic group appears after applying the suc cessive weighting procedure: Gayophytum (Epilobium-Boisduvalia). Results of the cladistic analysis support a sister group relationship of Ludwigia to the rest of the genera. The clade of Circaea, Fuchsia, and Lopezia is the sister group of the rernaining genera (except Ludwigia), but there is relatively less resolution of the relationships arnong those genera (the tribes Onagreae, Epilobieae, and Hauyeae). The other rnain conclusions are that the positions of Hauya and Gayophytum are problernatic and not well resolved, and that the tribe Onagreae rnay be paraphyletic.
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TL;DR: Silica sprays markedly reduced the incidence and severity of bract necrosis (BN) of Euphorbia pulcherrima Willd.
Abstract: Silica sprays (Na 2 SiO 3 or SiO 2 .nH 2 O) markedly reduced the incidence and severity of bract necrosis (BN) of Euphorbia pulcherrima Willd. cv. Supjibi Red compared to plants not sprayed with silica. BN has been associated with low Ca concentrations or high K: Ca ratios in tissues ofbract margins. Silica had no effect on Ca or K concentrations in bract margin tissues, and BN was not associated with the macro- or micronutrient composition of bract margin tissues. Sixteen days after initial anthesis, nontreated and deionized-water-sprayed poinsettias developed a higher incidence of BN than did plants sprayed with Na 2 SiO 3 or CaCl 2 . However, sprays of 3.56, 5.34, and 7.12 mM Na 2 SiO 3 were as effective as 9.98 mM CaCl 2 sprays in protecting against BN of 'Supjibi Red' and 'Angelika White' bracts for up to 30 days after initial anthesis. 'Supjibi Red' developed a higher incidence of bract necrosis than did 'Angelika White', but both cultivars showed a similar response to the treatments and similar symptoms of necrosis. In both cultivars, initial symptoms appeared as small necrotic lesions on bracts at the looped ends of lateral veins that displayed a closed-vein pattern after the plants reached initial anthesis.
39 citations
Journal Article•
TL;DR: Within the dicot flora, anomocytic type is most dominant found in 54 taxa, followed by paracytic and diacytic type, represented by 9 and 3 taxa respectively, whereas, parallelocytic, cyclocytic and anisocytic types are found only in one species each.
Abstract: Stomatal morphology of 69 dicot species distributed in 64 genera and 28 families was examined by light and scanning electron microscopy. In all 6 types of stomata i.e., anomocytic, paracytic, diacytic, parallelocytic, cyclocytic and anisocytic were recognized. Within the dicot flora, anomocytic type is most dominant found in 54 taxa, followed by paracytic and diacytic type, represented by 9 and 3 taxa respectively. Whereas, parallelocytic, cyclocytic and anisocytic types are found only in one species each.
39 citations